Coronary CTA: image acquisition and interpretation.

Computed tomography (CT) of the heart, because of ongoing technical refinement and intense scientific and clinical evaluation, has left the research realm and has matured into a clinical application that is about to fulfill its promise to replace invasive cardiac catheterization in some patient populations. By nature of its target, the continuously moving heart, CT coronary angiography is technically more challenging than other CT applications. Also, rapid technical development requires constant adaptation of acquisition protocols. Those challenges, however, are in no way insurmountable for users with knowledge of general CT technique. The intent of this communication is to provide for those interested in and involved with coronary CT angiography a step-by-step manual, introducing our approach to performing coronary CT angiography. Included are considerations regarding appropriate patient selection, patient medication, radiation protection, contrast enhancement, acquisition and reconstruction parameters, image display and analysis techniques and also the radiology report. Our recommendations are based on our experience which spans the evolution of multidetector-row CT for cardiac applications from its beginnings to the most current iterations of advanced acquisition modalities, which we believe herald the entrance of this test into routine clinical practice.

CT for imaging coronary artery disease: defining the paradigm for its application.

Current generation multidetector-row CT (MDCT) enables high-resolution, motion-free imaging of the heart within a single, short breath-hold. MDCT allows highly accurate and reproducible quantification of coronary artery calcium, a marker that has been used for the detection, exclusion and monitoring of coronary atherosclerosis. The exact role of coronary calcium measurements for cardiac risk stratification remains unclear to date. At contrast enhanced MDCT coronary angiography coronary arteries can be visualized with unprecedented detail. The accurate non-invasive assessment of the presence and degree of coronary artery stenosis appears within reach. With increasing accuracy MDCT enables non-invasive patency evaluation of coronary artery bypass grafts and coronary stents. The cross-sectional nature of contrast enhanced MDCT coronary angiography allows assessment of the vessel wall and may permit more accurate quantification of total atherosclerotic plaque burden than measuring calcified components alone. For a limited time, future technical improvement will be pursued mainly by accelerated gantry rotation speed and additional detector rows. However, novel concepts of CT image acquisition are already under investigation and may bring about yet another quantum leap for medical CT. This communication discusses potential approaches for the beneficial utilization of MDCT for the assessment of patients with known or suspected coronary heart disease.

Electrocardiographically gated 16-section CT of the thorax: cardiac motion suppression.

Thirty patients underwent 16-section multi-detector row computed tomographic (CT) angiography of the thorax with retrospective electrocardiographic gating. Institutional review board approval was obtained for retrospective analysis of CT scan data and records; patient informed consent was not required. Images reconstructed at six different time points (0%, 20%, 40%, 50%, 60%, 80%) within the R-R interval on the electrocardiogram were analyzed by two radiologists for diagnostic quality, to identify suitable reconstruction intervals for optimal suppression of cardiac motion. Five regions of interest (left coronary artery, aortic root, ascending and descending aorta, pulmonary arteries) were evaluated. Best image quality was achieved by referencing image reconstruction to middiastole (50%-60%) for the left coronary artery, aortic root, and ascending aorta. The pulmonary arteries are best displayed during mid- to late diastole (80%).

Multislice CT angiography.

The introduction of multislice CT into clinical radiology constitutes a quantum leap that significantly widens the scope of vascular CT imaging. The advances over conventional spiral CT have been quantitative, mainly in terms of increased image acquisition speed which provides unprecedented volume coverage and spatial resolution. Moreover, significant technical innovations, such as cardiac scanning capabilities, have brought about a qualitative shift towards applications that were thought to be beyond the scope of CT imaging. This way multislice CT offers a wealth of new opportunities for quickly and accurately diagnosing suspected vascular disease in all organ systems; however, as we move towards faster and faster image acquisition techniques, we are also facing new challenges that require development of novel strategies in order to take full advantage of the increased capabilities of multislice CT in its current form and future generations of CT scanners.

Multidetector-row CT of the heart.

Despite worldwide efforts aimed at primary and secondary prevention, heart disease is still the leading cause of death in the western world. There is great interest in developing tools for noninvasive assessment of the presence and degree of coronary artery disease. The advent of multidetector-row CT allows high-resolution volume coverage of the entire thorax and motion-free imaging of the heart and adjacent vessels within one breathhold. An exciting application with significant potential for cardiac risk stratification, which may overcome the obvious limitations of coronary calcium imaging in the future, is the use of the cross-sectional nature of contrast-enhanced multidetector-row CT coronary angiography for assessment of total coronary artery plaque burden.